Manufacture of sensitized photographic printing paper and cloth



Patented May 16, 1939 I UNITED STATES PATENT OFFICE MANUFACTURE OF SENSITIZED PHOTO- GRAPHIC PRINTING PAPER AND CLOTH John Holden, Reddish,Stockport, England No Drawing. Application February 26, 1938, Se-

iialvNo. 192,891. In Great Britain February 2'1, R Q U D 93 V O 7Claims. (CI. 956) This invention has reference to the manufacmanner witha solution of the following compoture of sensitized photographicprinting papers sition: and cloths and refers particularly to papers and200 gms. ferric ammonium oxalate. I cloths of the type used for makingwhat are t u 15 gms. borax are dissolved in water and made called blueprints by the ferroprussiate process, u t a v 1 r 500 d t m 1 5 and hasfor its object to provide an improved g z 2 5 so paper in which a bettercontrast between the re a e 30 gms. potassium ferrocyanide. white linesand the blue background is obta ned 25 0t 1 I Hi and which paper willalso keep without deteriorap ass um e cya'm 10 on, for long periods 30 m-dpotazsium toxalatel dissolveidsom water 10 The present inventionproduces an improved 25 an a? e g q g i of paper or cloth which can bedeveloped or washed ti n 8 so ved in e a We in the usual manner but isalso particularly suitme u able r pr d ing prints by the so called semi-The total volume of the finished solution is dry process of developmentin which a thin made up to 1000 cos. 15

film of liquid is applied as a developer to the surface as distinct fromthe common wet or Example H Washing developing Operation A suitable rawpaper is coated on one side with According o s invention a 9 -1 cloth alight sensitive ferroprussiate or blue print for the making of blue-pr nis m by 8-1)- solutlon, according to Example I and dried, the 20 p y t0the Surface One more Solutions In dry sensitive surface is then dustedover in any neutral or alkaline conditions, containing an ironconvenient manner h as b means of a felt salt, an iron-cyanogen compoundwhich may be pad with a dry powder of the following commsieither aferri-cyanide, a ferro-cyanide, or both, i tion: buffer salts and anitrite, in one solution, or the s 5 nitrite being applied in a separatesolution. 100 8 118- sulphondichloraminobenzoic acid; The invention canbe carried out in several nee starch powder ways as hereinafterexemplified, and the nitrite Excess of powder is removed by means of fat used is a nitrite of a suitable metal or base, which rotating brushesin light cuntact with the D will act as an acid absorbing agent whencalled dered urfa The powder adheres in and/or upon to do so; that is tosay it has a quantitive on the surface in the form f a r layer notreaction with acids or acidic salts with which it easily removed bymechanical fri tion comes in contact before exposure to light and whenexposed to light under a aesign the COIISfBQIIEIItIY will keep W Palm: 9cmth in the prints are washed in water, development takes lequlledneutral alkalme condltmnplace in the usual manner but afterwards the Italso will counteract the acid nature of some oxidising agent being onlyslightly soluble g i gig g fgg ig gggg fig g g n z g fi fif menles toact on the llight blue background and tensification and will alsocounteract theacidity igg g g gg g gg 3' ig g gz fi a: of prints whendeveloped by acidic or acld-conmg acaelerated by heat taining developersby the semi-dry process in 40 which a developer is applied to theexposed print. mp III In addition to: the acid absorbing properties, thenitrite when in contact with acids or acidic f gg g flg g g i fi g g igg mg zggggf salts has an oxidizing action which in some insmon. kstances may assist in the intensification of the print. 400 gms. ferricammonium oxalate.

A chlorate may be used to provide a mild oxigins. borax. dizing action.

The coated or sensitive surface may be coated The above are dissolved inwater to volume with a developing or intensifying oxidizing agent or1000 to which is added 5 in the form of a fine dry powder, such a powder140 gms, potassium ferrocyanide.

being e. g. a per-oxide of an alkaline earth metal, 30 potassiumferricyanide,

a h nochlo ite, pe -su pha e, a chlo substi- 125 gms. potassium oxalate(neutral). V tution derivative of an aromatic sulphonamide 250 potassiumm at or Fax ohrolmatef. m d1 to th in Water to a volume of 3000 00s.

am as o wor n accor n e vention are as follow 8 8 To the mixed coldsolutions there is added Example I gms. sodium nitrite.

Asultabie paperiscoatedinanyoonvenient dpapersomparedisalterenpc sure tolight under a design with a solution of the following composition- 100gms. zinc sulphate.

100 gms. mono sodium orthophosphate. 100 gms. magnesium sulphate.

30 gms. ammonium persulphate. Water to a volume of 100 ccs.

The solution is preferably applied by mechanical means such as bycontact with a roller re- 0 be necessary to make one or two tests toarrive at the most suitable quantity to make the best and most lastingprints.

Example IV A suitablepaper is coated in any convenient manner with asolution of:

50 gms. soluble starch. 25 gms'. sodium nitrite.

1 litre of water,

and the paper is then dried,and

the nitrite.

The nitrite and the chlorate may be in nonaqueous solutions and may beapplied at any convenient stage. Care must be taken by the use of buffersalts, mild alkalis or other suitable means to prevent its, or theirpremature decomposition.

afterwards coated with the solution in Example I without.

It has been found that achlorate and a nitrite together are particularlyuseful in the manufacture of "blue print papers which it is desired todevelop without the usual washing operation.

The chlorate stabilizes the blue background and the nitrite assists inthe formation of clear white lines, and also helps to keep the paper ingood condition before use.

What I claim as my invention and desire to secure by Letters Patent is:

1. Blue print paper suitable for producing prints by the semi-drydevelopment process having on its surface a non-acid coating comprisinga soluble iron salt, an iron-cyanogen compound, a buffer salty and asoluble nitrite.

. 2. Blue print" paper as defined in claim 1, in which the soluble ironsalt is a ferric salt and the iron-cyanogen compound is a ferrocyanide.

3. Blue print paper as defined in claim 1, in which the soluble ironsalt is a ferrous salt and the iron-cyanogen compound is a fern-cyanide.

4. Blue print" as defined in claim. 1, in which the coating comprisesboth ferroand ferri-cyanides.

5. "Blue print paper as defined in claim 1,

in which'the coating comprises a soluble chlorate.

6. Blue print paper" as defined in claim 1, in which the nitrite is anitrite of an alkali metal.

'l'. A'methodfor preparing blue print paper winch comprises applying tothe paper a nonac'id' coating. solution containing a soluble iron salt,aniromcyanogen compound, a bufier salt and a soluble .nitriteydrying thecoated paper, and applying an oxidizing developing agent in the form ofa fine dry powder.

JOHN HOLDEN.

